Color television



2 Sheets-Sheet 1 N .mmm N Oct. 2, 1945. G. c. szlKLAl COLOR TELEVISION Filed Nov. 29, 1943 2 Sheets-Sheet 2 QMQ Mm.

INVENToR. G50/Q65 c. SZ//fm/ BY 57 A TTORNEY Patented Oct. 2, 1945 cocon mnvrsloN George C. Saiklai, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware "Pllim Nwember 29, 1943, serial No. 512,151 A 10 Claims. (Cl. 178-5.4)

'Ihe present invention relates to systems for the reproduction of television images in natural colors, and more particularly to a color television system in which signals representing diierent colors are generated and used simultaneously to reproduce an image in color.

In practicing the present invention, sets of modulated signals, each representative of the presence and intensity of one of the primary colors of the view or object to beptransmitted, are derived by color separation apparatus at the transmitter by any known method and apparatus. These sets of modulated signals are transmitted simultaneously by any known method and are separated and applied at the receiver in a novel manner in accordance with this invention to provide a brilliant projected reproduction at the receiver.

Therefore, the primary object of the present invention is to provide a novel color television systemcapable of reproducing an image of a view or object brilliantly and in natural colors.

Another object of the present invention is to provide a novel color television system capable of reproducing an image of a view or object on a projection screen.

A further object of the present invention is to provide a. novel television receiving system in which sets of modulated signals representing one or more colors control the amount and color of light transmitted from a light source to a viewing surface. l

Still another object is to provide a novel image reproducing tube for reproducing images in natural color of a scanned object or view.

jecting images in color in accordance with the invention. 'Ihe tube il is equipped with two cathode ray gun structures I4 and i6 for developing beams of electrons II and I9. The gun Il is provided with a control electrode or grid 22 for modulating the beam Il, and the gun I6 is provided with a grid 23 for modulating the beam l l. Horizontal and vertical deilecting coils 24 and 2t are connected to horizontal and vertical deflection generators 21 and 28 to produce scanning action of the beam Il in a manner which is well known. The horizontal and vertical deflecting coils Il and 32 associated with electron gun It are shown as A further object of the present invention is to provide a novel light controlling device for transmitting light of a predetermined color and intensity. y

YA still further object of the invention is to provide a novel image reproducing tube having a, light controlling device for transmitting light of a predetermined color and intensity.

The foregoing and other objects of the invention will appear from the following description of several illustrative embodiments thereof.

Fig. l is a diagrammatic showing of a system embodying the invention for reproducing an image in the natural colors of the original;

Figs. 2 to 6 illustrate in detail a portion of the apparatus employed inthe system of Fig. 1.

In Fig. l there is showna. television receiving apparatus having an image reproducing tube l0, provided witha light controlling device indicated in its entirety by reference character I2, for probeing connected in series with the coils 2l and 26 so that the same denection current traverses the two coils connected in series thereby simplifying the operation of the deection system. It will be understood however that electrostatic deilection may be employed.

A television system arranged in this manner but having a uorescent screen receiver tube and apparatus and circuits for obtaining televisionv transmission and recepon is shown in a patent to Bedford 2,191,121, granted February 2?, 1940. The deection and control circuits shown and described therein and in a patent to Vance, 2,137,039, granted November 15, 1938, or in a patent to Toison et al, 2,101,520, granted December 17, 1937, may be employed in connection with the tube I0 of this invention. The various electrodes of the electron guns I 4 and li of the tube il are to be supplied as usual with suitable operating potentials. This may be done as shown in the Bedford patent above referred to.

A radio receiver 3l suitable for the reception of television signals from a more or less distant transmitter and equipped with the usual selective circuits, ampliers, and a demodulating device is connected as shown so that its output is furnished to a video signal separator 3i. In the system selected for illustrating the invention, .this arrangement is so designed that where incoming video signals are modulated in accordance with the several colors of the original subject, such as a view or object, these signals will be separated into two distinct sets, one representing the signals produced when the original is scanned through a, red color lter, for example, and the other representing signals produced when the original is scanned through a green color filter, for example.

Signal separation of the red and green signals may be accomplished by transmitting these signals as modulations of two different frequencies and selecting these modulated frequencies by tuned circuits.

vis employed at the transmitter for developing signals representing two colors, for example, it

will be understood that signal storage will be necessary at either the transmitting station or at the receiver to store one of these sets of color modulated signals so that it may be released simultaneously with reception of the other color modulated signal so that the grids 22 and 23 of the tube III will be affected simultaneously with signals representing different colors. Signal i storage may be accomplished by providing separate storage equipment, or by relying on the capability of modern camera tubes to store signals. An example of such a modern tube is the rthicon.

As shown in the illustrativeA example, modulated signals representing the red portion of the original are amplified in a video signal amplifier 39 and are applied to the grid 22. Likewise, the

remaining signals representing a different color, for example green, are applied to the grid 23 by way of video signal amplifier 4I.

The demodulated signal from the radio receiver 34 is applied in the usual manner to a synchronizing separator 43 which separates the horizontal and the vertical pulses normally present in the demodulated television signal so that these may be applied to the horizontal and vertical ysynchronizing controls 44 and 46 respectively to control the operation of the previously mentioned horizontal and vertical deflection generators 2I and 28. This general arrangement for synchronizing a receiver is shown in detail in the Bedford patent referred to above and has been described herein merely for the sake of completeness of the disclosure.

The light controllingI arrangement I2 referred to previously comprises a xed screen or raster 5I and radiant energy sensitive screens or rasters 52 and 53. 'I'he relative positions of these rasters and the marks thereon are shown in Figs. 5 and 6 of the drawings, Fig. 6 illustrating the operation of the light controlling device. It will be understood that Figs. 5 and 6 may be considered as sectional views of the light controlling arrangement I 2, as viewed from a position above the tube I0 in Fig. 1 of the drawings., The position of the tube and the angularposition of the light controlling device in the tube may, of course, be varied.

Figs. 2 to 4 of the drawings taken together may be considered as a vertically exploded view of the light controlling arrangement I2. The stationary raster 5I and the radiant energy sensitive rasters 52 and 53 are similar to the stationary and radiant energy sensitive rasters disclosed and claimed in applicants copending application,

' Serial No. 512,160, filed Nov, 29, 1943, entitled Method of and apparatus for producing luminous images. `In order that the disclosure of the present invention may be complete, the demoving the beam. Therefore, it will be seen that v since the successive positions of both of the beams are controllable in Fig. 1, the distortion will occur in small selected successive areas. The beams Il and I9 are preferably moved concurrently and impinged on small areas on each side of the device I2 which are in register or substantially in register so that an image substantially in the natural colors of the original may be projected by light transmission upon a viewing screen 56.

Light for this purpose which is projected through the transparent wall 59 of the tube onto the light controlling device I2 is obtained from a light source 56. A reflector 62 and a light con- -denser 64 concentrate the light and also insure a uniform distribution of the light on the surface of the device I2. A lens or lens combination or diffusor 66 projects an image of the device I2, or at least luminous portions thereof, onto the screen 56. With diffused light behind the light controlling device, the picture in colors may be viewed directly.

By selecting the dierent elements of the optical arrangement shown by way of example, the size of the image on the screen 56 may be controlled with respect to the size of the light controlling ldevice I2. It will be understood that the diagrammatic showing of Fig. 1 is not intended to indicate with accuracy the optical train involved or the relative size of the parts. For example, the screen 56 and the image on the screen may be very large in proportion to the total area of the light controlling device I2.

'Ihe stationary raster 5I may, for example, be formed by employinga sheet of transparent or translucent substance, such, for example, as glass, mica, transparent or translucent plastics, or a Wire mesh, etc. An opaque substance (Figs. 3, 5, and 6) of any kind is applied to the surface of the material comprising the raster 5I. It will be seen from Fig. 3 that this opaque substance is applied in the form ofr strips 69 so that these strips alternate with transparent strips 1I. This substance may be applied photographically or by any known contact printing process, such as typographical or intaglio printing or by a lithographic process. The rasters 52 and 53, shown more in detail in Figs. 2 and 4 respectively, which are radiant energy sensitive, and more particularly, physically deformable upon impingement of a cathode ray beam, are preferably in the nature of thin supported or unsupported films.

As an example, each of the films composing the' merous factors such as the radiant energy beam intensity will be considered in determining the thickness of either deformable raster for a given purpose.

The material of which each rasteriilm 52 or 53 is composed is selected primarily in view of its high temperature coefficient of expansion. The film may be composed of cellulose acetate, cellulose nitrate, or a film of gelatin. A liquid known as Parlodeon, obtainable commercially, gives good results in practice.

In preparing the film with Parlodeon, the commercially obtainable liquid may be poured on water so that it forms a thin film on the surface of the water. 'Ihis thin lm maybe lifted from the surface of the water upon which it floats. Cellulose acetate and cellulose nitrate are obtainable commercially in thin iihn form, and seli. supporting gelatinous films are also obtainable. 'I'he radiant energy sensitive raster 52, however it may produced, is provided with marks or strips 14 (Fig. 2) alternating with the strips 16 of the exposed translucent film material. For the raster 52 in a two color television system such as is illustrated by way of example in Fig. 1, the coating material of the strip 1l is green in color so that green light or approximately green light is transmitted through these strips. 'I'he radiant energy sensitive raster 53 is also provided with marks or strips 'Il alternating with the strips Il of the exposed transparenter translucent illm material. 'I'he material forming the strips 'Il is red in color so that red light orapproximately red light is transmitted by these strips when this raster is used with the raster 52 in the two color system shown by way oi' example. Referring to Fig. 5, it will be seen that the rasters 52 and 53 are located with respect to the raster 5I so that the opaque strips 69 on the raster 5| register with the transparent strips 16 and 'I8 of the rasters 52 and 63. For purpose of illustration, the marks or strips 69, 14, and 11 are shown as completely impregnating the material of each raster. However, as pointed out above, it will be sumcient for the purpose of the invention, if these strips are merely printedl on the surface of the raster.

Figs. 5 and 6 taken together in conjunction with Fig. 1, illustrate the principle of operation of the light controlling device to reproduce colored images. Assume, for example, that twocolor television signals are being received by the radio receiver 34, these signals representing the red portions and green portions respectively of the eld of view or object scanned at the transmitter. These signals will be separated during operation in known manner by the signal separator 36. 'I'he signals representing the red portions of the original subject are amplied, if desirable or necessary, in the ampliiier 39 and are applied to the grid 22 of the electron gun structure Il associated with the green raster 52. The signals representing green portions of the original are or may be amplified in the amplifier 4I and applied to the grid 23 of the electron gun structure I6 associated with the red raster 53. The beam deflection means 24 and 26 and 3I and 32, associated with each gun structure, cause the cathode ray beams I8 and I9 to simultaneously scan the device I2. The beam I8 scans the'raster 52, and the beam I9 scans the raster 53. Also, while the light filters and rasters are bluish-green and orange-red they are referred to as green and red for convenience. l

While reference is made herein to red portions of the original and green portions of the original and signals representing these portions, it will be understood that these signals also are generated in varying degrees of modulation by varying shades or hues of green and red.

When the electron beams I8 and I9 are cut off from both guns by a blanking voltage or other blanking means, the screen 56 will appear dark since substantially no light will get through the triple raster. When the beam I8', controlled by the red signals, impinges on the green raster 52, it will open up in relation to the other. rasters in the manner shown in Fig, 6 of the drawings by reason of heat expansion. A spot of red light will then appear on the screen 56. In a like manner, when the beam I9 heats the red raster 53 under control of the green signals, the red raster will open up in relation to the other rasters and a green spot will appear on th'e screen` I6. According to the amount of red and greenlight transmitted, combinations representing. other colors present in the original may be obtained. 'I'hese combinations of colors may be designated as "beatcolorsl With the red raster 63 open, the opening of the green raster 32 to various degrees will produce diierent shades of greenl to white through pale With the red raster 53 closed, the observed color will go 'from green to blackV through the dark greens. When the green raster is completely open, shades of red from obtained. g

With the red and green rasters open completely, a bright yellow will be obtained. As the red and green rasters close, the observed colors will be tan. brown, and black.

The-lines on each raster within the aspect ratio may be greater in number than the number of horizontal lines into which the image of the viewed subject is divided or the horizontal lines multiplied by the aspect ratio, in which case the vertical line structure of the device I2 will not limit the resolution to a degree greater than it is limited by the horizontal lines. l Where interlaced scanning is employed of the character described in a patent to Ballard, No. 2,152,234, granted March 28, 1939, the thermal capacity of the red and green raster can retain its deformation during the cycle of interlacing when the beam is cut off. In this manner the guns I8 and I9 may operate alternately as the optical effect will be the same in accordance with the invention as though these beams operated concurrently.

For more rapid cooling, and therefore for less.

image persistence, the raster 5I may be used as a heat conductor, and it may, in order to enhance this effect, be provided with radiating iins on the outside of the tube I 0.

Where the interlaced scanning system is'em ployed for interlacing the red and green scanning cycles, thedeilection coils connected in series', as shown, provide for the same current flowing in each series connected deiiecting coil, and therefore interlacing of successive red and green scan-4 nings will be obtained in a simple and eilective manner.

As disclosed above and also in the copending application referred to herein, it is possible to pro-` vide the lines upon the several rasters by a pho`` tographic process. In order that this may be done accurately. a large screen may be provided which has alternate dark and light stripes of suitable width thereon. A much reduced image of this screen may be projected upon a sensitized sheet of material which is to'be used for any one of the rasters, and the latent photographic image may then be developed so as to provide alternate transparent strips and dark or colored strips which have the desired degree of iineness` in spacing and in width. The rasters 52 and 53 can be given the desired color by tinting them'to the required colors or converting a silver image raster or screen structure intoan appropriately colored dye image by methods well known in thev color photographic art.

Various modifications of the system shown and described herein by way of example are possible without departing from the spirit and scope of the invention described herein, and itis desired that any and all of such modiiications be considered whitethrough pink may be within the purview of the present invention defined by the hereinafter appended claims.

Having' nowdescribed the invention, what is claimed and desired to be secured by Letters Patent is the following:

l. In a system for reproducing, images incolor, a source of illumination, a viewing screen, a light controlling device interposed between said screen and said source, said light controlling device including a relatively undistortable screen, a red screen distortable on'application of heat and a green screen distortable on application of heat, meansy for heating said red screen in successive localized areas under control of a green image signal modulated heat source, and means for heating saidgreen screen in successive localized areas under control of a red image signal modulated heat source whereby to produce'in cooperation with said relatively undistortable screen a luminous image in colors on said viewing screen.

2. In a system for reproducing images in color, a source of illumination, a viewing screen, a light controlling device interposed between said screen and said source, said light controlling device including a relatively undistortable screen, a red rscreen distortable on application of heat and a green screen distortable on application of heat, means for heating said red screen in successive localized areas under control of a green image signal modulated heat source, and means for simultaneously heating said green screen in the same successive localized areas under control of .i

vand said source, said light controlling device including a relatively undistortable raster, a distortable red raster and a distortable green raster, means for scanning said red raster with a green image signalx'nodulated cathode ray, and means for scanning said green raster with a red image signal modulated cathode ray whereby to produce in cooperation with said relatively undistortable screena luminous image in colors on said viewing screen.

4. In a system for reproducing images in'color,

a source of illumination, a viewing screen, a cathode ray tube having therein a light controlling device interposed between said screen and said source, said light controlling device including a relatively undistortable raster, a distortable r red raster and a distortable green raster, means in said tube for scanning said red raster with a green image signal modulated cathode ray, and

means in said tube for scanning said green raster lwith a red image signal modulated cathode ray whereby to produce in cooperation with said relatively undistortable screen a luminous image in colors on said viewing screen.

5. In a color television system, means for receiving signals representing portions of a given color of an image, means for receiving signals representing portions of another given color of the image. a' cathode ray tube having scanning means providing a scanning ray, means for modulating the ray from said scanning means by one set of said received signals, a multiple light valve comprising sections expandable upon application of heat thereby to be responsive to radiant energy in said tube having one element thereof responsive to-said ray and capable of passing light of a predetermined color upon activation by said ray, a second scanning meansin said tube providing a second scanning ray, said multiple light valve having a second ray sensitive element therein responsive to said second ray and capable of passing light of a predetermined color upon activation by said second ray, means for modulating said second ray with signals representing said second color, and means for illuminating said multiple light valve wherebyy a luminous image is produced upon concurrent activation of said ray responsive elements of said multiple light valve by said scanning rays.

6. In a color television system, means for receiving signalsrepresenting red portions of an image, means for receiving signals representing green portions of the image, a cathode ray tube having scanning meansv providing a scanning ray, means for modulating the ray from said scanning means by said received red signals, a multiple light valve comprising sections expandable 'upon application of heat thereby to be responsive to radiant energy in said tube having one element thereof responsive tov said ray and capable of passing green light upon activation by said ray, a second scanning means in said tube, said multiple light valve having a second ray sensitive element therein responsive to said second ray and capable of passing red light upon activation by said second ray, means for modulating said second ray with said greensignals, and means for illuminating said multiple light valve whereby a luminous image is produced upon concurrent activation of said.` elements of said multiple light valve by said scanning rays. f

7. A color determining iight valve comprising a xed element, a deformable element disposed on one side ofsaid xed element, said deformable element permitting light of a given color only to pass upon deformation thereof, and a second deformable element on the other side of said stav vtionary element, said second element permitting light of another given color to pass upon deformation thereof.

I8. A color determining light valve comprising a fixed screen element having alternate opaque and light transmitting portions, a radiant energy sensitive deformable element disposed on one side of said fixed element, said deformable element permitting light of a given color only to pass upon deformation thereof, a second radiant energy sensitive deformable element on the other side of said stationary element, said second element permitting light of another given color to pass upon deformation thereof'.

9. The light valve of claim 8 in which said deformable elements are in the form of a membrane having a degree of thinness suchthat it expands readily upon impingement of a cathode ray beam.

l0. A color determining light valve comprising a fixed screen element having alternate' opaque and light transmitting portions, a deformable element disposed on one side of said'xed element having alternate opaque and red light transmitting portions, said deformable element permitting red light to pass upon deformation thereof, and a second deformable element on the other side of said stationary element having alternate opaque and green lighttransmitting portions, said second element permitting green light to pass upon deformation thereof, said red and green light transmitting portions being disposed in register with said light transmitting portions of said fixed screen element.

- GEORGE C. SZIKLAI. 

